What is class of “p” here ? class of “p” is double or cell?

Question

My code is below

r=1*10^3
c=1*10^-6
num=[-1]
dnum=[r*c 0]
sys=tf(num,dnum)
num1=[-r*c 0]
dnum1=[1]
sys1=tf(num1,dnum1)
subplot(211)
step(sys)
subplot(212)
step(sy